1. Field of the Disclosure
The disclosure concerns a rear loader road milling machine with a milling roll.
2. Related Technology
In the field of road construction, especially in preparation and maintenance of surfaces with traffic on them, road milling machines are generally used for producing traffic area surfaces.
Typical road milling machines include a chassis supported on wheels or on chain mechanisms. Furthermore, a milling roll is provided in the chassis, which is arranged in a roller housing, which is open on the bottom, i.e., in the direction of the road surface. In order to transport away the material removed by milling (referred to herein as “milled material”), road milling machines typically have a transport device through which the milled material can be introduced into an accompanying truck with a corresponding loading area. In so-called “rear loaders,” the milled material is introduced into the truck through the rear of the road milling machine; in the case of a “front loader,” the milled material is transported through the front of the road milling machine to the truck.
In order to work the road paving, road milling machines are typically sunk below the road paving, so that the rotating milling roll protruding from the roller housing comes in contact with the road paving; sinking is usually done through lifting the wheels on which the chassis of the road milling machine is supported.
When the rate of rotation of the milling roll is relatively high, the milled material is highly accelerated. This presents problems, especially from the point of view of work safety, since the working personnel could be injured by the milled material thrown out. Moreover, it is possible that the milled material is thrown under the wheels that carry the chassis, resulting in damage to the wheels and changes in the milling depth and the milling pattern. When the milled material arrives outside the milling track, it is no longer collected by the stripping device. Then the milled material must be collected with a sweeper, which requires an additional step in the process. In order to overcome these disadvantages, different attempts were made in the past to prevent the throwing out of milled material.
In order to prevent throwing out of the milled material through the side, road milling machines may have a roller housing of which has side plates on both sides, the height of which can be adjusted, this is called “edge protection.” This system proves to be useful, since throwing out the milled material on the side is of only lesser importance due to the direction of rotation of the milling roll.
In order to prevent the milled material from being thrown out toward the rear, that is, against the direction of travel, stripping devices have been used. These include a plate-shaped stripper arranged behind the milling roll, the essential task of which consists in stripping the milled material remaining on the milled surface so that it can be introduced into a transport device and will not remain on the processed surface.
The area in front of the milling roll in the direction of travel is problematic. Here, especially at low milling depths, a large opening is present between the front part of the roller housing and the road surface, through which the milled material can be thrown out toward the front and also to the sides.
DE 197 39 915 C2 describes a raised verge milling aggregate in which a splashboard and baffle plate are rigidly arranged in front of the milling roll in the direction of travel, so that the majority of the milled material thrown out toward the front is collected or is diverted in the direction of the rear of the known aggregate. However, the known aggregate has the disadvantage that the milling depth is limited due to the rigid arrangement of the splashboard and baffle plate. Moreover, an opening facing in the direction of travel remains between the lower edge of the splashboard and baffle plate and the subsurface through which milled material can be thrown toward the front and also to the sides.
In order to solve the problems described above, rubber skirts which extend downwardly starting from the front part of the roller housing have been developed. Such rubber skirts are flexible so that they can be deform depending on lowering of the road milling machine and thus on the milling depth. Such rubber skirts should lie against the road surface during the milling process, independently of the milling depth, so that there is no opening between the front part of the roller housing and the road surface. However, a disadvantage is that such skirts in practice do not provide sufficient sealing against the thrown out milled material, especially at low milling depths. Thus, the skirts tend to deform in a wavy pattern so that tight contact is not provided. Also, the skirts are subject to great wear.
Since rubber skirts provide insufficient sealing, shield arrangements were developed in which a rigid, mostly metallic shield can be guided in vertical guides, perpendicularly to the road surface to be processed, in front of the opening between the front part of the roller housing and the road surface. Thus, the known shields can be adjusted in height, depending on the milling depth, where the adjustment is done through insertable bolts or by suspension on a chain. Although the shields used show a greater stability against the milled material whirling in front of them, especially at low milling depths, a distance between the shield and the road surface always remains, even though it is smaller, so that still parts of the milled material can be thrown out toward the front and also the sides. This is to be attributed to the fact that the known shields must not lie directly on the road surface since, in the case of unevennesses of the road surface, for example, in the case of waviness of the road surface or when crossing of already existing milling tracks, this can lead to hindering of the advance, if not to complete blocking of the advance, which is to be attributed to jamming of the shield in the road surface.